Pro Powerful and flexible code review
Code reviews can be done via Pull Requests, or simply commit-by-commit. There are voting rules, random reviewers pools, and smart comment invalidation logic. Pull requests are also versioned so it's easy to review partial changes after the author has updated his code.
When you create a Pull-request you can add set of reviewers. They all have to vote and approve the PR. There's some flexibility on how the voting is accepted, it can be majority wins, or all-agree. Good practice is to add BOT accounts like jenkins, that also will vote on the review, based on for example tests run, and can forbid a merge because of a negative vote. In addition users can leave special type of comments that will also prevent merges, aka TODO notes. Once TODOs are resolved a Pull Request can be merged.